Users of the services provided by a telecommunications system are assigned to identifiers, which are commonly used for addressing and identification purposes. In legacy telecommunications systems a user was usually assigned to a single identifier. However, this tends to change in modern telecommunications systems, where the same user can be addressed (e.g. called) and identified (e.g. before another user when establishing a communication with him) by more than one identifier. The use of more than one identifier per user in a telecommunications system does not necessarily increase the traffic in the system; rather, it allows a telecommunications operator to deliver more personalized services, which can be adapted, e.g., according to a profile associated to each identifier.
An example of a telecommunications system providing such a feature is a Universal Mobile Telecommunications System, UMTS, comprising the—so called—Internet Protocol IP Multimedia Subsystem, IMS, e.g. as described in 3GPP Specification TS 23.228 V8.0.0 (March-2007). Chapters 4.3.3.2 (“Public User Identities”) and 4.3.3.4 (“Relationship of Private and Public User Identities”) in TS 23.228 disclose how a IMS user can be assigned to more than one “Public User Identity” PUB-ID as identifiers.
According to the standardized procedures, a communication can start to be established with a user by receiving in nodes of the IMS a service request for establishing a communication (e.g. a Session Initiation Protocol message “INVITE”) comprising a PUB-ID assigned to said user, which is then processed according to the user profile associated to said PUB-ID.
Following with the illustrative case of IMS, a further kind of identifiers are also considered. These are the —so called—“Public Service Identities” PSIs. As disclosed in chapter 4.3.6 of the aforementioned TS 23.228, a PSI differs from a PUB-ID in that it identifies a particular service (or a particular service instance of a service) hosted e.g. by an application server, rather than a particular user. Both, PUB-IDs, as well as well as PSIs, take preferably the form of Session Initiation Protocol Uniform Resource Identifiers, SIP-URIs, or “telephony” URIs, TEL-URI. According to the standardized procedures, service requests comprising PSIs are routed in the IMS system using essentially the same routing mechanisms as service requests comprising PUB-IDs of users.
Recently, the—so called—“Wildcarded PSIs” have been also considered for use in IMS systems, which take also the same format (SIP-URI, TEL-URI) as PSIs. A Wildcarded PSI identifies a collection of (distinct) PSIs which belongs to its range. For example, a Wildcarded PSI such as “sip:chatlist!.*!@example.com”, would identify PSIs such as:                sip:chatlist1@example.com        sip:chatlist2@example.com        sip:chatlist42@example.com        sip:chatlistABC@example.com        
etc.
A service request comprising a distinct PSI belonging to a collection of identified by a Wildcarded PSIs is essentially processed in the IMS system as one more PSI. However, a significant advantage provided by the use of Wildcarded PSIs, is that they enable optimization of operation and maintenance procedures in a IMS system.
For example, for each and every PUB-ID or PSI, the Home Subscriber Server HSS of a IMS system has to store a set of data (called “service profile”) which are needed for the processing service requests related to said PUB-ID or PSI in the IMS, such as registrations, multimedia session requests, etc. For a given PUB-ID or PSI these data can comprise, among other: the Serving Call Session Control Function S-CSCF assigned to mediate in sessions originating or terminating in the user/service identified by said PUB-ID or PSI; a set of structured information -called “Initial Filter Criteria” IFC, which establishes execution triggers that allows processing a service request comprising said PUB-ID or PSI according to predefined rules; other related (public and/or private) identifiers; etc. Furthermore, these service profile data has to be downloaded from the HSS to the corresponding S-CSCF and stored therein, so as to properly serve service requests comprising said PUB-ID or said PSI.
However, there is no need of storing and maintain such a service profile for each and every distinct PSIs that belongs to a collection identified by a particular Wildcarded PSI, as only a—say—generic service profile data is stored for a Wildcarded PSI, which is applicable to all the distinct PSIs identified by (i.e. belonging to) it. Accordingly, a HSS can perform the master storage of the service profile data of a given Wildcarded PSI, which can be then downloaded to a particular S-CSCF that will mediate in all service requests comprising any distinct PSIs belonging to the collection identified by the Wildcarded PSI.
Therefore, not only operation and maintenance procedures are simplified, but the quantity of data needed to be stored for some users of the IMS system can be significantly diminished by using Wildcarded PSIs; thereby, allowing optimize the usage of the storage resources, for example, in HSSs and S-CSCFs of the system, while providing essentially the same kind of services to users that can be assigned to, and identified by, distinct PSIs belonging to a Wildcarded PSI. As it is readily apparent, these advantageous features are equally applicable in other telecommunications systems, not necessarily comprising a IMS system, and having to deal with identifiers that belong to a particular collection identified by a given further identifier.
Wildcarded PSIs have been envisaged for use in Virtual Private Network VPN scenarios using IMS as a connectivity/services core network; wherein a particular VPN can e.g. be globally associated to a Wildcarded PSI, while each of its users can be individually assigned to distinct PSIs belonging to the collection identified by the Wildcarded PSI. In these scenarios the users of, e.g., a IP-based Private Exchange IP-PBX can get access to multimedia communication services through a IMS system, to which (distributed or centralized) premises of the IP-PBX are connected (e.g. via border gateways), as if they were individually subscribed to it.
The advantageous features provided by the use of Wildcarded PSIs promise an early adoption by telecommunications operators owning IMS systems, which could then increase their business opportunities by offering, for example, VPN services to other service providers. Accordingly, it should be desirable minimizing the impact due to implementation of Wildcarded PSIs for a telecommunications operator owning a IMS system.